DE1515751A1 - Enamelled stranded conductor for tubular cables - Google Patents

Description

Dr.-Ing. Wilhelm Reichel

Frankfuri / Main-1.

PaikslraßelS ■, _} ^ xjj ^ ßi · ²⁹⁸⁰

General Cable Corporation, Hew York, II. Y./U.S.A.

Enamelled stranded conductor for high-level cables

The invention "relates to an improved concentrically stranded cable ladder for tubular cables" and a method for producing such a cable ₀

The object of the invention is to produce a concentric stranded cable ladder in which the individual copper conductors are semi-hard and separated from the neighboring conductors or wires are insulated by means of an enamel coating. The advantages according to the invention resulting therefrom will become clear in the following description.

A cable harness, which consists of concentrically stranded wires in a semi-hard state, is characterized according to the invention: that the wires are insulated from one another by an enamel layer and the enamel layer consists of a material, that hardens at a lower temperature at which the wires are tempered. The material decomposes at soldering temperatures and preferably consists of a polyurethane enamel.

The invention also provides a method for producing a concentrically stranded cable conductor after the wires as long be pulled until they are semi-hard and then stranded concentrically; the procedure is characterized by it from that a number of wires are enameled, that the coated wires at a temperature for drying the Enamel are fired, which is below the annealing or tempering temperature of the wires, that then the coated wires be stranded with uncoated wires to produce the cable, in which the individual wires are separated from adjacent wires are insulated by an intermediate enamel coating;

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the material for the enamel coating is selected so that it hardens below the temperature at which the wire is tempered and that it decomposes at soldering temperature; the material is preferably polyurethane.

This construction provides the tensile strength required when pulling long pieces of the finished cable into a pipeline guaranteed. The concentrically stranded cable, in which each wire is isolated from the other, eliminates the effect of self-capacitance. If the concentrically stranded cable is housed in a steel tube, the skin effect remains essentially of the same order of magnitude as a cable in air; the self-capacitance effect remains in contrast to cables with segment-shaped Ladders Hull, their skin and self-capacitance effect almost twice as large as the values for air when they are housed in a steel tube. The cumulative skin and The self-capacitance effect of the concentrically stranded conductor in a steel pipe is of the same order of magnitude as in one segment-shaped conductor in the same environment. Furthermore, the cumulative skin and self-capacity effect is an enamelled one concentrically stranded wire considerably less than with the conventional concentrically stranded cable, with the bare cable Wire is used when it is to be housed in a steel tube.

After the cable manufacturing process, the copper wires are deformed until they are in a semi-hard state. This degree of hardness is achieved through a suitable selection of the drawing operations. Each wire is enameled, preferably Polyurethane enamel and dried or fired at a temperature at which the wire is not yet soft-annealed. The wires are therefore not tempered or calibrated during the drying or firing of the enamel, but remain in their semi-hard state so that they are suitable for the specific technical application Retain required tensile strength.

The wires can then be stranded to produce the cable ladder, the cable insulated in the usual way and inserted into a steel tube.

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to be pulled. The enamel insulates adjacent wires to that to ensure the desired electrical behavior, and prevents the copper wire from touching the insulating oil in order to prevent it Ensure durability.

Since the reduction of the self-capacitance effect and the okin effect can already be brought about by an insulation cover between adjacent wires, it is sufficient to only use the Cover wires that touch each other in the assembled cable. The actual execution of a ladder at 127 Wires can look like this:

Center wire bare

6-wire layer - all wires enamelled

12-wire layer - alternately bare and enamelled

18-wire layer - all wires enamelled

24-wire layer - alternately bare and enamelled

30-wire quality - all wires enamelled

36-wire layer - alternately bare and enameled

To circumvent the harmful effects of copper on oil mi you can the wires are made of aluminum, tinned copper or copper coated with a lead-tin alloy.

The invention is described in detail below with reference to the drawing which shows it by way of example.

Pig. 1 is a perspective view of one according to the invention manufactured cable.

Fig. 2 shows schematically the process for enamelling the Wires.

Figure 3 is a schematic representation of the equipment used in making such a cable.

In Figure 1, a cable ladder 10 is shown with a number of individual wires 12, which are stranded in the usual way to form a concentrically stranded conductor. The wires 12

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consist ^ fupfer in the semi-hard state, so that the conductor has the required Has tensile strength to withstand the stresses when pulling the cable into a tube. Because big Cable lengths must be drawn into a tube, e.g. B. a length of 3,000 feet (= 914 m), is the semi-hard state of the conductor wires essential for the required tensile strength.

The individual wires are insulated from one another by an enamel coating. This enamel is advantageously polyurethane enamel, which is applied to the wires before stranding to form a cable ladder. The polyurethane enamel is burned to dry. However, the firing temperature is kept below the tempering temperature of the wire in order to maintain the semi-hard state of the stranded wire To maintain wire.

The stranding is done in a similar way to the usual concentric stranded conductors with bare wires. The electrical performance of the enameled cables according to the invention However, it is superior to the usual concentrically stranded conductors and is essentially equivalent to the known segment-shaped conductors, when they are drawn into a steel tube.

The wire cable, which is stranded concentrically in the usual way, has a high skin and self-capacitance effect. A segmented wire cable (ie 4 segments) reduces both the skin and self-capacitance effects by approximately 40 % of the values for a concentric wire cable in air. If the segmented wire cable is operated in a steel pipe, the values double compared to those in air.

In the case of an enamelled, concentrically stranded cable ladder according to the invention, the skin effect remains the same as in the usual concentrically stranded cable, while the self-capacitance effect is eliminated. Inside a steel tube in addition, the ukin effect of the enamelled concentrically stranded cable is not increased. Lies inside a steel tube the cumulative skin self-capacitance effect in an enamelled

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th, concentrically stranded cable in the same order of magnitude as a segmented cable.

In addition to the fact that the polyurethane enamel can be fired at a temperature that is lower than the tempering temperature for the individual wires, this enamel has the significant advantage that it can be heated at a temperature on the order of molten solder (approximately 600 I ^s ) decomposed and the parts of the decomposed material have a flux effect. Thus, the concentrically stranded enamelled conductor can be spliced in a simple manner and provided with the usual soldered bonds.

It is not necessary to enamel all of the wires. It only the individual wires need to be isolated from each other. For example, the main conductor 16 can be bare; all wires 18 of the 6 wire layer should be enameled; the wires 20 in the 12-wire layer can alternate between bare and be enamelled; all of the wires 22 of the 18-wire layer should be enamelled; the wires 24- in the 24-wire layer can be alternately bright and enamelled; all of the wires 26 in the 30 wire layer should be enameled and the wires 12 in the 36-wire layer can alternate between bare and be enamelled. The bare wires in the 36-wire layer make electrical contact with the electrically conductive cover which is usually above the cable ladder. The enamel naturally isolates the copper in each one Wires from the oil and thus prevents the harmful effect on the oil. In such applications, the bare wires made of aluminum, tinned copper or copper coated with a lead-tin alloy to keep the copper touching with the oil to prevent.

A typical plant for wire production is schematically shown in FIG shown.

The wire 28 is drawn through a die 30 to the required thickness. This usually happens in a number of

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Drawing passes with intermediate annealing. The whole drawing process is like this applied that the wire is in a semi-hard state when it has reached the required thickness.

The wire passes through an applicator device 32 in which a thin layer of enamel is applied to the wire. The device is preferably a common magnetic wire enamelling machine »

The enamel must dry below the tempering temperature of the wire or harden and decompose at the soldering temperature to allow easy splicing of the cable. For the time being turn out Polyurethane enamels are the most suitable for this purpose. The available polyurethane enamels consist of a mixture a blocked isocyanate plastic, a polyester and a suitable solvent. The bound isocyanate is an adduct of three moles of toluene diisocyanate, 1 mole of hexanetriol and 3 moles of phenol. The polyester used is made of from 2.5 mol of adipic acid, 0.5 mol of phthalic acid and 4 ha of a triol. The proportions of the two components are 233 Parts of polyester and 100 parts of isocyanate.

The liquid enamel polymerises and forms the polyurethane film when it burns immediately after coating. The blocking agent (blocking agent) of the isocyanate is removed at temperatures above 140 ⁰ C, whereafter the polymerization may begin.

The wire is fired in a furnace 34 and wound onto a reel 36. The reel has the usual dimensions for use in stranding machines. The temperature must be above the drying or firing temperature of the polyurethane enamel, but below the tempering temperature of the copper wire. When using an approx. 7 m long oven with a wire speed of approx. 4.3 m / min and an oven temperature of approx. 293 ° G, which is customary for this purpose, a wire (No. 8 A.w'.G. = 3.26 mm 0) exposed to the oven temperature in four cycles for a period of about 400 seconds.

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Some commercially available polyurethanes contain polyamide material. Such polyurethanes can also be used as long as the drying or firing temperature is low and the enamel decomposes at the temperature of the molten solder. In this application, the term polyurethanes is not intended to refer to the particularly described composition, but also the commercially available polyurethane compositions with which he » required low firing temperature and the decomposition properties.

The enameled wire can then be put in a concentric stranding machine be stranded according to Figure 3.

In FIG. 3, a typical arrangement for producing a concentrically stranded conductor is given in a schematic representation. The central strand 16 is passed through a concentric stranding machine 38 which consists of a number of wire stranding heads 40 to apply the required number of concentric turns of copper wire from the wire reels 36 on each head on the central strand. J'ecle reel 36 can carry enameled wire. On the other hand, alternating reels, as indicated above, can be wound up clantsi · [■.> - ■ '.Λ , which consists of aluminum, tin-plated copper or copper coated with its lead-tin alloy »Plating of the copper wire is preferred in order to prevent bare copper wire from coming into contact with oil, which would lead to deterioration of the oil.

This method offers the option of connecting the cable conductor with the required high tensile strength and with the desirable properties of the individually insulated wires.

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Claims (14)

Patent claims 1 ο cable with concentrically stranded, hard wires, d a ■ characterized in that each wire is insulated from the "adjacent wire" by a layer of enamel, that the enamel layer consists of a material which is below the wire tempering temperature dries or hardens and decomposes at soldering temperatures. 2. Cable according to claim 1, characterized that the alternating wires in the outer Wire layer are bare. 3. Cable according to claim 1, characterized in that the alternating wires in alternating Stranding layers are bare. 4- "Cable according to claim 3, characterized that the bare conductors are made of aluminum. 5. Cable according to claim 3, characterized in that the bare conductors are made of tin-plated Made of copper. 6. Cable according to claim 3, characterized in that the bare conductors are made of a lead-tin alloy coated copper. 7. Cable according to claims 1 to 6, characterized that the material is polyurethane enamel. 8. A method for producing a cable according to claims 1 to 7, wherein the wire is drawn to a semi-hard state and the wires are stranded concentrically, characterized in that that a plurality of wires is covered with an enamel that decomposes at soldering temperatures, 909830/0501 BATH ORIGINAL -9- 1615751 that the coated wires are used to dry or harden the enamel burned below the wire tempering temperature and that the coated wires with bare wires for the manufacture of the cable be stranded. 9. The method according to claim 8, characterized that all wires are enamelled, 10. The method according to claim 8, characterized in that aluminum is used for the bare wires will. 11 «Method according to claim 8, characterized in that that the bare wires are coated with tin. 12. The method according to claim 8, characterized in that that the bare wires with a lead-tin alloy covered v / earth. 13. The method according to claim 8, characterized in that the bare wires only in the outer Layer of cable to be stranded alternately with enamelled wires. 14. The method according to claims 8 to 13, characterized in that that the majority of the wires are covered with polyurethane enamel. 909830/0501 Blank page